Method of inhibiting rust and corrosion in a fuel oil tank



United States Patent 3,304,267 METHOD OF INHIBITING RUST AND CORROSIONIN A FUEL OIL TANK Leo D. Miller, 33 Claudet Way, Eastchester, N.Y. 10709 No Drawing. Continuation of application Ser. No. 861,185, Dec. 22,1959. This application Apr. 13, 1964,

Ser. No. 361,322

1 Claim. (Cl. 252389) This is a continuation application of applicationSerial No. 861,185, filed December 22, 1959, now abandoned, entitled,Rust and Corrosion Inhibitor for Fuel Oil Tanks.

The present invention relates to a rust and corrosion inhibitor for fueloil tanks and, more particularly, it relates to a shaped solid rust andcorrosion inhibitor which prevents formation of rust on the metal wallsof the tank, which eliminates the corroding ability of impurities in thefuel oil, and which serves to expel continuously from the tank thoseimpurities which cause rust and corrosion.

Corrosion and rusting of fuel oil tanks is not caused by the fuel oil inthe tanks but rather by the presence of varying amounts of impuritiesthat enter the fuel tanks under normal operating conditions. Theseimpurities are the sulfur and sulfur compounds in the fuel oil and thewater droplets that are present in the tank. When the tank is partlyempty, there will be a certain amount of moisture containing air in thetank. This moisture will condense as water droplets on the walls of thetank. Since the water is heavier than the oil in the tank, the waterdroplets will roll down the metal tanks walls through the oil to thebottom of the tank. In passing through the oil, the water dropletscollect and carry along with them particles of sulfur and sulfurcompounds that are present in the oil. In time the sulfur impuritieswill dissolve in the water to form sulphurous and sulphuric acids. Thisacidulated water in the tank will then cause corrosion and rusting ofthe fuel oil tanks.

To attempt to solve this problem powder type rust and corrosioninhibitors have been provided which are distributed throughout the oilin the oil tank. These powder type inhibitors, however, pass out of thetank with the oil and clog the nozzle, strainer and other working partsof the oil burner or else pass out entirely with the oil before theyachieve their purpose.

In accord with my invention, I have provided a compressed or moldedshaped solid containing ingredients which prevent rust and corrosion offuel oil tanks and which further disperses the water in the tankthroughout the oil so that the oil may be expelled in an emulsifiedstate from the tank in small and harmless quantities. The shaped solidcontains sodium metasilicate, a rust inhibiting alkaline salt and an0n-ionic dispersant of the alkylphenyl ether of polyethylene glycoltype. This shaped solid is heavier than oil so that it will always befound in the bottom of the fuel oil tank where the water, if any, willcollect. Moreover, the shaped solid is water soluble and oil insolubleso that it operates only in the presence of water. If no water ispresent in the tank, the inhibitor will lie inactive at the bottom ofthe tank until such time as Water collects in the tank.

Accordingly, it is an object of the present invention to provide a rustand corrosion inhibitor for use in fuel oil tanks, which inhibitor is ina compressed or molded solid shape and which operates only when water ispresent in the fuel oil tank.

Another object of the present invention is to provide a rust andcorrosion inhibitor for use in fuel oil tanks which is in the form of ashaped solid and which is able to disperse any water in the tankthroughout the oil medium.

Another object of the present invention is to provide a rust andcorrosion inhibitor for fuel oil tanks which is heavier than oil so thatit may sink to the bottom of the fuel oil tank.

A still further object of the present invention is to provide a rust andcorrosion inhibitor of the above described character which renders afuel tank rust proof by protectively coating the walls thereof and bycausing the continuous elimination of any water collected in the tank.

One advantage of my novel rust and corrosion inhibitor is that it servesto prolong the life of a fuel oil tank by eliminatnig rust andcorrosion.

Another advantage of my novel rust and corrosion inhibitor is that iteliminates the use of aqueous rust inhibitors, which only serve to addmore water to the fuel oil tank.

A further advantage of the present invention is that it eliminates theuse of the powder type rust and corrosion inhibitors.

A still further advantage of my novel rust and corrosion inhibitor isthat it in no way affects the burning quality of the fuel oil.

Additionally, my novel .rust and corrosion inhibitor has the advantagethat it will, due to its shape and weight, find the lowest part of theoil tank where the water in the oil tank eventually collects,

Other objects and advantages of the present invention will become moreapparent as it is described in detail below.

My novel rust and corrosion inhibitor contains from to by weight of arust inhibiting alkaline salt as, for example, sodium nitrite, sodiumcitrate, sodium carbonate, sodium bicarbonate, sodium chromate, sodiumphosphate, lithium citrate, lithium carbonate, lithium bicarbonate, 5%to 15% by weight of sodium metasilicate, and from 5% to 15% by weight ofa non-ionic dispersant which is a mixture of condensation products ofalkylphenols and ethylene oxide wherein the alkyl group has at leastfour carbon atoms.

These non-ionic dispersants that I employ are described in Patent No.2,213,477 to Steindorlf et al. The above described non-ionic dispersantsare commonly referred to as alkylphenyl ethers of polyethylene glycol.

When the rust and corrosion inhibitor is dropped into a fuel oil tank,it will descend to the bottommost part of the tank where any collectedwater will be located. The inhibitor will dissolve in the water andliberate the sodium metasilicate and the rust inhibiting alkaline saltso as to alkalize the water. Once the water in the tank is alkaline,corrosion and rust will immediately cease. In addition, the inhibitorcauses a protective coating to form on the metal walls of the tank.

If no water is present in the tank, the inhibitor will lie at the bottomof the fuel oil tank until such time as water collects. This is becausethe ingredients comprising the inhibitor are insoluble in oil andsoluble in water and because the shaped solid inhibitor is heavier thanoil. When water collects on the bottom of the tank, a proportionate partof the solid shape will dissolve to alkalize the water and provide aprotective coating on the tank walls which are exposed to the water.

Ordinarily, a non-ionic dispersant of the alkylphenyl ether of thepolyethylene glycol type would induce corrosion and rusting. However,the presence of the rust inhibiting alkaline salt and sodiummetasilicate keep the water in the tank on the alkaline side therebyreversing the tendency of the non-ionic dispersant to induce corrosionand rust. Moreover, the dispersant remains stable and free to form anoil-water emulsion. The dispersant gradually reacts with the watermolecules in the salt solution to form oxonium complexes that arereadily dispersable in the fuel oil medium. These oxonium complexes willform due to the presence of multiple close ether linkages so that theresultant compound is easily dispersed throughout the fuel oil when theoil is agitated. Thus, when fresh fuel oil is placed into the empty orpractically empty tank, the water will be dispersed as an emulsionthroughout the fuel oil medium and will more or less permanently remainin this state. Accordingly, small quantities of water will becontinuously eliminated from the tank as the fuel oil is used andwithout affecting the burning quality of the oil.

In order to test the effectiveness of my novel composition, cleaned,polished and weighed metal coupons of SAE 1010 steel, 1" x 2" x 1/16",were immersed in closed jars containing Fuel Oil #2 and test solutions.The solutions consisted of water, water plus 0.1% inhibitor and waterplus 0.5% inhibitor. The metal coupon in each jar was suspended in suchfashion that a portion was immersed in both the fuel oil and the testsolution. In all cases, the fuel oil was the top layer and the testsolution was the bottom layer.

The tests were performed in triplicate, that is, three separatecorrosion assemblies for each test solution. The entire series ofcorrosion assemblies were stored at 180 F. for 200 hours. At the end ofthe test period, the metal coupons were removed, Washed with benzol andalcohol, dried and then weighed. The corrosion results are reportedbelow in terms of loss in weight in milligrams.

The results of these tests will be found in the following table.

The data of the above table clearly demonstrates the effectiveness of myrust and corrosion inhibitor.

As one example of my rust and corrosion inhibitor, I provide a shapedsolid containing 80% 'by weight of a rust inhibiting alkaline salt, byweight of sodium metasilicate and 10% by weight of a non-ionicdispersant which is the condensation product of alkylphenols andethylene oxide. The ingredients may be compressed or molded in anyconventional manner into a shaped solid.

It is important that the inhibitor be in the form of a shaped solid. Theuse of an aqueous solution of the ingredients of my novel compositionwould be preclude-d because it would only serve to add more water to thetank.

It is also impossible to employ the ingredients in powder form becausethe mixture of ingredients have different specific gravities, some ofwhich are less than that of fuel oil. Accordingly, the ingredients wouldseparate and float on top of or within the fuel oil and fail to reachthe bottom of the tank so that they could act together to prevent rustand corrosion. However, when the composition is employed as a compressedor molded shaped solid, the aggregate has a specific gravity greaterthan oil. Thus the inhibitor will sink through the oil and reach thebottom of the tank where the water layer is located.

The shaped solid can be in the form of compressed or molded tablets,blocks, sticks, cones, balls or any other similar shape. However, it ispreferable to employ a shape such as a sphere which will permit theinhibitor to roll to the bottom-most portion of the tank. It is thisarea that the inhibitor must reach to be operative.

Similar results may be obtained if other oil insoluble non-ionicdispersants in place of the condensation products of alkylphenolethylene oxide are used.

While the invention has been described in detail above, it is not to belimited thereto. Hence, it is desired to cover any and all forms andmodifications of the invention which may come within the language andscope of the appended claim.

I claim:

The method of inhibiting rust and corrosion in a fuel oil tank having abottom, sides, ends and a top, which in normal operation thereof hasfuel oil periodically withdrawn and admitted to maintain a reservoir ofoil in said tank, and wherein an aqueous layer containing watersolublecorrosive impurities, collects in a layer underlying oil in said tank,said method comprising: introducing into said tank a solid bodyconsisting essentially of sodium metasilicate as a binder, in amountfrom 515% by weight, a substantially water-soluble rust and corrosioninhibiting alkaline salt, selected from the group consisting of sodiumnitrite, sodium citrate, sodium carbonate, sodium bicarbonate, sodiumchromate, sodium phosphate, lithium citrate, lithium carbonate, lithiumbicarbonate, in amounts from -85 percent by weight, and an alkyl phenylether of polyethylene oxide and phenol water-in-oil emulsifying agent inamount from 515% by weight, said solid body being sufiiciently heavierthan oil to sink through the oil into said aqueous layer, said alkalinesalt dissolving in said aqueous layer, said water-in-oil dispersantcausing said aqueous layer together with said water-soluble impuritiesand said therein dissolved inhibitor to disperse in said oil, wherebysaid inhibitor becomes distributed to portions of said tank normallysubject to rust and corrosion, and said corrosive materials dispersed insaid oil are withdrawn from said tank together with said oil during thenormal operation thereof.

References Cited by the Examiner UNITED STATES PATENTS 1,565,043 12/1925Avis 14822 XR 2,114,923 4/1938 Holstead 252-387 XR 2,213,477 9/ 1940Steindorff et al.

2,522,447 9/ 1950 Harris.

2,529,177 11/1950 Nieland et al. 252-- XR 2,795,560 6/1957 Williams.

2,824,059 2/ 1958 Chamot.

OTHER REFERENCES Corrosion of Metals, by Evans, Second Ed., 1926,published by Edward Arnold & Co., London, pages 112 and 113.

The Condensed Chemical Dictionary, 5th Ed., 1956, Reinhold PublishingCo., New York, pages 998 and 1006.

LEON D. ROSDOL, Primary Examiner.

JULIUS GREENWALD, Examiner. M. WEINBLATT, Assistant Examiner.

